Thermostat



March 24, 1942. F. s. THOMAS 2,277,275

THERMOSTAT Filed Fb. 17, 1939 2 Sheets-Sheet 2 Patented Mar. 24, 1942THERMOSTAT Frank S. Thomas, Topeka, Kans., assignor of one-half to FredP. Martin, Topeka, Kans..

dpplication February 17, 1939, Serial No. 256,918

2 Claims.

This invention relates to thermostats adapted for insertion within flowlines of boilers, stills, and other appliances, and has for itsprincipal object to provide a thermostat of this character which isaccurate in operation and not subject to being insulated through calciumdeposits and It is'a further object of the invention to prol vide athermostat structure wherein the heat responsive elements form a owchannel so that they may have direct surface contact with a heated owline or vessel in which the thermostat is v Inserted.

In accomplishing these and other objects oi the invention, ashereinafter described, I have provided improved details of structure,the preferred form of which is illustrated in the accompanying drawings,wherein:

Fig. l is a vertical section through a portion of a steam generatorhaving a steam outlet tube or flow line equipped with thethermostat'constructed in accordance with the present invention.

Fig. 2 is a vertical section on the line 2--2 of Fig. 1.

Fig. 3 is a horizontal section through a adapted for operation by thethermostat.

Fig. 4 is a cross-section through the thermostat elements on the lined-d of Fig. 1.

Fig. 5 is a detail section showing the thermostat elements and theirattaching flanges in spaced relation to each other and the housing withwhich they are connected.

Referring more in detail to the drawings:

While my invention is adapted to many-uses, I have illustrated it asapplied to a steam generator I having a steam outlet tube 2 locatedwithin the heat zone of the generator and through which steam isdischarged tol a steam line 3. The tube 2 is slidable through a bushing4 in the wall of the generator to compensate for expansion andcontraction occurring therein or the steam coils with which it isconnected. The tube 2 projects through the wall of the generator andvalve carries a fiange 5 that is welded thereto as indicated at S and l.

The thermostat embodying the features of the present invention issupported by the tube 2 and includes telescoping, tube-like thermostaticelements 8 and 9. The outer member t is' of such size that it is snuglyslidable within the tube 2, and the inner tube 8 is similarly engaged inthe tube 9 so that the adjacent inner and outer suri faces of therespective tubes are in close contact with each other to prevententrance of foreign matriel therebetween and to efect conduction of'heat from the generator through the tubular members. 'I'he inner member9 is welded to the outer tube 9 at the inner ends'thereof as indicatedat II). The opposite end of the inner member vprojects from the member9'for mounting a iltting or head II. The corresponding end of the outermember 9 also carries. a flange I2 secured A by welding, as indicated atI3 and I6.

The tubular members 8 and 9 are formed of materials having differentcoefcients of expansion. For example, the inner tube 8 may be formed ofinvar or other material having a low coeficient of expansion, while theouter tube 9 is formed of a material having a high coeihcient ofexpansion, such as brass, so that when the tubes are subject totemperature change relative movement occurs therebetween for effectingactuation of a system of levers, later described.

The head or fitting II is illustrated as weide to the member 8 andincludes a T having a cleanout branch I5 aligning with the axis of theinner tube and which is closed by a plug I6. 'I'he fitting also has alateral branch Il that is connected to the pipe 3 by a union I8. Thefitting also has spaced lugs I9 and 2U forming a guide-.I way 2l for asliding block 22, later described.

23 designates a lever supporter housing enclosing the fitting II, andwhich has a wall 24 proi is attached by suitable fastening devices, suchas y y screws 32. 'I'he bottom wall 2l has a slotted opening 33 to pas'sthe branch I1 and to allow for expansion and contraction between theinnermost member of the thermostat and the tube 2.

The housing is secured to the flanges 5 and I2 by fastening devices 34.The fastening devices 34 have their Shanks 35 extending throughregistering openings in the respective anges and into threaded sockets36 as clearly shown in Fig. 1. A suitable gasket 31 is clamped betweenthe flanges to provide a leak-proof joint.

Extending transversely and having support Within bosses extendinginwardly from the side walls 23 and 29 is a shaft 3l mounting a rocklever 39. The lever 39 has a depending arm 40 provided with afork-shaped end 4l engaging over the sliding block 22, previouslymentioned, the fork of the lever being connected with the block by a pin4I extending therethrough., The rock lever also includes an upwardlyextending arm4 42 of longer length than the depending arm so that thefree end moves through a greater arc responsive to movement of thethermostat, as later described. 'I'he arm 42 terminates in a head 42which bears against the base 44 of a compounding lever 45, the leverbeing pivoted oma cross shaft 4l, similar to the shaft 38, vabovedescribed. The compound lever includes a relatively long depending arm41 having a head 48 engaging against the end of a plunger 49, theplunger 48 being slidably mounted in a bushing 50, carried by the coverplate 3|. It is thus obvious that shifting movement of the block 22 withthe head I l is multiplied through the system of levers so that theplunger 49 is caused to move a much greater distance. Vertical movementof the block in the guideway 2| compensates for arcuate movement of thelever` without lost motion.

The plunger 49 may be utilized for actuating i various devices, but ishere illustrated as adapted for operating a rock lever to eiect closureof a valve 52, the rock lever 5l being pivoted on a suitable bracket 53carried by the cover plate 3l, the valve being also mounted on the coverplate and arranged so that the stem 54 thereof is adapted to be engagedby an adjusting screw 55 car.

rled by the rock lever as clearly shown in Fig. 1.

With the structure thus described it is obvious that the lever supportor housing 23 is fixed to the tube 2 and adapted to move therewithresponsive to any expansion and contraction occurring therein withrespect to the wall of the generator. It is further obvious that theflange I2 on the outer thermostat element is anchored to the flange 5 ofthe tube 2 so that the outer end of the tubular member 9 has xedrelation with the outer end ofthe tube 2. Thereforeexpansion andcontraction occurring therein eiect movement of the inner member 8 inthe direction of the axis of the respective members. -Since the housingand lever supporting shafts are carried by the tube 2, relative movementoccurs between the housing and the head I l to eifect rocking movementof the lever 39 and the compounding lever on their respective shafts toeffect actuation of the plunger and rock lever 5l to operate the valvein suspending and permitting ilow of fluid therethrough, for example,fuel supplied to the heating appliance o1' the generator.

From the foregoing it is obvious that the thermostatic tubes being inclose sliding contact with each other and with the tube 2, there is noopportunity for entrance of foreign material that would tend tointerfere with relative movement' thereof or produce inaccurate movementby reason of any insulating effect of the accumulated foreign matter andthat the heat within the generator acts directly through the walls ofthe respective tubes and is not blocked by calcium deposits or the likeas there is,no room for such deposits between the respective tubes.Moreover, since the fluid passing through the tube 2 sweeps the innersurface of the inner thermostatic element, it is kept substantially freeof deposits. The thermostatic elements are, therefore, subject totemperature of the gases of combustion flowing aroundv and sweeping thetube 2 so that the resultant temperatures are effective in actuating thelevers to open and close the valve or other operating mechanism to whichthe thermostat may be connected. It is also obvious that theconstruction of the thermostat avoids a false relative movement betweenthe temperature responsive elements due to any foreign substance thatmight collect therein.

What I claim and desire to secure by Letters Patent is:

1. A thermostat mechanism for fluid heating devices having a heatingchamber and afiow duct contained in said chamber in direct exposure toheating medium in said chamber including, lever carrying meansexteriorly of said chamber, a lever pivoted on said carrying means, arigid connection between the duct and said carrying means .to bodilysupport said carrying means from said duct, and a plurality oftelescoped tubes sleeved within said duct with the outermost of saidtubes rigidly anchored with respect to said carrying means and theinnermost tube having free relative movement with respect to saidcarrying means and connected with said lever, said telescoped tubeshaving' different coeihcients of expansion from each other and beinginterconnected to provide relative movement between said tubesresponsive to temperature of the heating medium acting upon said ductand modied by the temperature of fluid ilowing from said duct throughthe innermost tube to produce said relative movement between theinnermost tube and said carrying means for actuating said lever.

2. A thermostat mechanism for fluid heating devices having a heatingchamber and a flow duct contained in said chamber in direct exposure toheating medium in said chamber including, lever carrying meansexteriorly of said chamber, a lever pivoted on said carrying means, arigid connection between the duct and said carrying means to bodilysupport said carrying means from said duct, a plurality of telescopedtubes having surface to surface contact with each other and sleevedwithin said duct with the outermost of said tubes in surface to surfacecontact with the duct, and means rigidly anchoring the outermost tubewith respect to said carrying means, said innermost tube havingconnection with said lever and free relative movement with respect tosaid carrying means, said telescoped tubes having diiferent coefiicientsofexpansion from each other and being interconnected so'that relativemovement between said tubes responsive to temperature of the heatingmedlum acting upon said duct and modiiied by the temperature of fluidflowing from said duct through the innermost tube produces said relativemovement between the innermost tube and said carrying means foractuating said lever.

FRANK sfrHoMAs.

